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We Cannot Use Chemistry: Using Bacteria to Kill Weeds on Organic Farms

Thu., Sep. 29, 2022 1:15 p.m. - Thu., Sep. 29, 2022 2:30 p.m.

Location: ED 315

The Department of Chemistry and Biochemistry Presents:


Dr. John Stavrinides, Department of Biology, University of Regina


Organic producers face unique agricultural challenges. Synthetic pesticides and fumigants including herbicides, fungicides, bactericides, and insecticides are not permitted to be used on organic farms, making pest control one of the more challenging aspects of organic farming. Canada thistle is a hardy weed that has been increasing steadily over the last 10 years in the prairie provinces. Canada thistle competes for light, water, and nutrients, which reduces crop yields substantially. For organic producers who cannot use synthetic herbicides to control Canada thistle, this weed becomes a serious issue. The objective of our research is to evaluate strains of the bacterial pathogen of Canada thistle, Pseudomonas syringae pv. tagetis, for potential development into a bioherbicide. We found that some strains caused substantial stunting and loss of biomass for 2-week-old Canada thistle plants, with multiple applications reducing Canada thistle plant emergence significantly.We also show that the plant host range of this strain is defined, suggesting it may be suitable for a few different crop plants grown here in Saskatchewan.